This series, though a bit over dramatized, are files from MUFON (a legit organization) brought forth for exploration and critical thinking.
The information brought forward, such as particular events, are fact, not conjecture, backed up from key witnesses that have come forward.
What I am surprised with however is, why they haven't brought Dr. Steven Greer into the mix with his 100's of top secret military govt. witnesses that have already come forward and their stories. Another point that is a negative in my opinion, is painting the ET's in an "aggressive" manner in one of the episodes and not telling the whole story (selective agenda), which is disappointing for MUFON, which is a respected organization. They may have had their hands tied by the History channel for propaganda effect...who knows.
Nonetheless, I highly recommend this series, for the knowledge/events brought forth. But if you want some real eye opening info, google disclosure project with Greer and follow the websites/rabbit hole.